Traditionally, absorbent articles have included a central absorbent element having a body facing side, a garment facing side, longitudinally extending sides and transverse ends. These articles generally include an absorbent core made of loosely associated hydrophilic materials such as wood pulp. These prior art products are held in place by providing areas of pressure sensitive adhesive on the garment facing side to adhere it to the inner crotch surface of the wearer's undergarment.
One drawback of prior art absorbent articles has been that in the course of wearing the absorbent article, the shape of the absorbent article tends to deform and the article tends to move out of position, thereby reducing its effectiveness. Recent designs have addressed this problem by including tabs or wings that extend laterally from the longitudinal sides of the central absorbent and wrap around the edges of the undergarment. See U.S. Pat. No. 4,285,343 (McNair); U.S. Pat. No. 4,589,876 (Van Tilburg); and U.S. Pat. No. 4,911,701 (Mavinkurve). However, the use of such tabbed articles presents several problems.
First, such tabbed absorbent articles were previously made with integral tabs by (i) cutting a tabbed article shape from an extra-wide strip of laminate formed from layers of body fluid pervious and impervious materials and (ii) inserting a central absorbent core between the layers. However, this method has several disadvantages. First, there is considerable wastage due to the excess material remaining after the tabbed article shape is cut from the large strip. Second, the tab material is limited to that suitable for an absorbent article cover.
Recently, absorbent articles have been developed which have separately formed tabs which are attached to the garment facing side of the napkin--see U.S. Pat. No. 4,900,320 (McCoy). Consequently, it would be desirable to develop a method and apparatus for forming such separate tabs and attaching them to absorbent articles which (i) made efficient use of tab material, (ii) allowed the tabs to be made from a range of materials beyond those suitable for article covers and (iii) provided flexibility in terms of the location and orientation of the tabs on the article.
The second problem associated with the use of tabbed articles arises because adhesive strips are typically applied to both the tabs and the central portion for attaching the article to the user's undergarment. These adhesive strips are often covered with separate protective release strips which act to protect the adhesive from dirt and unintended adhesion during manufacture, packaging and storage. These release strips must be removed by the user just prior to application of the product. Multiple adhesive elements and release strips, however, can present the user with a cumbersome process when preparing the product for use. The user often has to remove all three release strips (one on the central absorbent core and one on each of the tabs) while simultaneously making sure that the tabs do not inadvertently adhere to one another or to another part of the product. In particular, the user must carefully handle the product when removing the release strip on one tab in order to avoid inadvertently contacting the exposed adhesive on the other tab and the central portion, thereby rendering the product useless. Even when the problem of undesired adhesion is avoided, the user is presented with the task of disposing of three release strips.
Accordingly, absorbent articles have been developed in which a single release strip, coated on both sides with silicone or the like, is used to protect the adhesive strips on both the central portion and tabs, so that a single pull of a release strip is sufficient to ready the article for use--see U.S. Pat. No. 4,701,178 (Glaug et al.). However, such double sided release strips are more expensive than the standard single sided release strips and present problems in manufacture because they are difficult to handle due to the slipperiness of both of their sides. Thus, a need exists for a tabbed absorbent article having a user-convenient arrangement in which a single pull of a release strip is sufficient to remove the release material covering both the central portion and tab adhesive strips yet which utilizes standard single sided release paper.
A third problem is that even though the tabs help to stabilize the article, as a result of forces imposed on it during use, the article may still shift and deform, causing a phenomenon known as "roping," whereby the napkin is crushed transversely inward and its edges are curled around its longitudinal axis so that the napkin eventually takes on the appearance of a twisted rope. This situation causes discomfort to the user and a loss of product effectiveness. Although it is known to attach the tabs along the longitudinal edges of the central portion of an absorbent article--see U.S. Pat. No. 4,285,343 (McNair)--there is a need for an absorbent article having tabs which are attached to the longitudinal sides of the central portion in such a way as to aid the article in resisting such lateral deformation.